1. Field of the Invention
The invention concerns a method of making an electrical connection by gluing a rigid terminal to a conductive track.
It also concerns a rigid terminal for use in the method.
It applies in particular, although not exclusively, to making electrical connections for a heating plate or for a heating receptacle, in particular for a kettle.
2. Description of the Prior Art
One example of a heating plate is described in French patent application FR-A-2 692 426. A heating plate of this kind includes a metal support on top of which is a vitreous layer in turn supporting a resistive track. The latter is advantageously deposited by the silkscreen process and forms a heating element.
A heating plate of this type has many advantages. Firstly, it is particularly well suited to heating a kettle. It is easy to clean, which is also advantageous from the hygiene point of view, and offers high thermal efficiency. Because it is thin, it is easily disposed within a kettle.
In the above patent application, the electrical connections to the ends of the resistive track are glued, using a conductive material, as shown in particular in FIG. 3 of the application. To this end, a metal wire or tongue is embedded in a drop of conductive resin deposited on the conductive track. The resin is then dried and cross-linked.
For some specific applications it would appear desirable to use rigid metal terminals or similar devices rather than to glue the electrical wire directly to the resistive track. In particular, this method facilitates demounting of the plate, by disconnecting the power supply electrical wires, these wires being terminated by terminals complementary to the terminals glued to the resistive track.
Gases are generated during the drying and cross-linking of the resin. For gluing the terminal to the resistive track it is necessary to promote the flow of gas. Otherwise gas bubbles form under the solid surfaces of the terminals. These gas bubbles are trapped and make the contacts fragile, both mechanically and electrically.
However, we have found that the flow of the gases produced by drying and cross-linking the resin is satisfactory when stranded electrical wires are glued directly to the resistive tracks. This flow occurs under particularly good conditions if the diameter of the strands is in the range from 0.2 mm to 0.8 mm.
However, it is difficult to make a connection to a flexible electrical wire.